After you have laid a solid foundation in Yin and Yang, five lines of gossip and heavenly stems and earthly branches, it won't be so difficult to learn.
There are several schools of Feng Shui.
Personally, I suggest you start with Shao Weihua's Zhouyi and Prophecy, and with your original knowledge of eight characters, I think you will make rapid progress. This book is about six hexagrams.
Six hexagrams are convenient, and you can directly use hexagrams to measure Feng Shui.
With the six basic methods, you can learn geomantic omen quickly, and you can learn it together with "All geomantic omen should be avoided at home" and "Common sense and application of geomantic omen".